1. Field of the Invention
The present invention relates to a suspension, and in particular, to a suspension on which a magnetic head slider is mounted. Further, the present invention relates to a head gimbal assembly and a disk drive using the suspension.
2. Description of Related Art
A hard disk drive, which is data storage, includes a head gimbal assembly equipped with a magnetic head slider performing read/write of data to a magnetic disk which is a storage medium. FIG. 1 shows a conventional example of a head gimbal assembly 100.
The head gimbal assembly 100 includes: a magnetic head slider 101; a flexure 103 having a spring property equipped with the magnetic head slider 101 on the tip part thereof; an FPC 104 (flexible printed circuit) formed on the flexure 103, which transmits signals to the magnetic head slider 101; and a load beam 105 supporting the flexure. The load beam 105 is mounted on a head arm via a base plate not shown. Further, a plurality of head gimbal assemblies 100 are stacked and fixed to a carriage via respective head arms and pivotally supported so as to be driven rotationally by a voice coil motor to thereby constitute a head stack assembly (not shown).
The head gimbal assembly 100 is driven rotationally by the voice coil motor to thereby position the magnetic head slider 101 mounted on the tip part thereof. In recent years, however, due to an increase in recording density of a magnetic disk, positioning accuracy of a magnetic head provided by such a control is not sufficient.
In order to perform more precise positioning, a microactuator 102 for precisely driving the magnetic head slider 101 is mounted. The microactuator 102 is mounted on the tongue part 133 of the flexure 103. The microactuator 102 is formed in an almost U shape, including two arms which hold the magnetic head slider between them. When the two arms are curbed in right and left, the tip part of the magnetic head slider 101 sways, whereby precise positioning control of the read/write element mounted on the tip part can be performed. Note that the two arms are deformed in a curved manner when the PZT devices provided on the side faces of the arms are driven to be expanded or contracted.
As shown in FIGS. 2 and 3, the flexure 103 includes a flexure body 131 providing the tongue part 133 of the gimbal structure, and a separated part 132 providing flexure side terminals connected with read/write element side terminals of the magnetic head slider 101. They are integrally linked by the FPC 104 as shown in FIGS. 2 and 3. Specifically, the flexure body 131 includes two branched outrigger parts 132 extending to the tips side (part close to the separated part 132), and each of the two outrigger parts 132 is bent inward to be U-shaped near the tip to thereby form a linking part 133a. The outrigger parts 132 are linked to an almost rectangle tongue part 133 interposed between the two outrigger parts 132 at parts ahead of the U-shaped parts.
The flexure 103 is equipped with a trace 104 which applies a voltage to drive PZT devices provided to the arms of the microactuator 102. As shown in FIG. 2, the trace 104 is branched into two, same as the outrigger parts 132, and they are formed along the outrigger parts 132. Each of the branched traces 104 is formed in two paths. One path (reference numeral 141) extends up to the separated part 132 of the flexure 103 so as to be connected with the read/write element side terminals of the magnetic head slider 101, and the other path (reference numeral 142) extends to the actuator side terminal formed near the root of the arm of the microactuator 102. The trace 142 for microactuator is bent to be U-shaped near the tip of the flexure body 131, same as the outrigger part 132, and extends to the back end side of the tongue part 133 and is connected near the back end of the tongue part 133. Alternatively, the trace 142 for microactuator may be formed to extend directly to the connecting terminal for microactuator without passing the tip side, as shown in Japanese Patent Application Laid-Open No. 2002-74870 (Patent Document 1).
On the other hand, as the capacity of a hard disk drive increases in recent years, the recording density of a magnetic disk further increases. In order to cope with it, although a magnetic head slider of a size called pico slider was used in the conventional example described above, a smaller magnetic head slider of a size called femto slider is used. Further, one having a size called pemto slider, which is the size between a pico slider and a femto slider, is also used. In such a case, for the tongue part 133 of the flexure 103 on which such a small magnetic head slider is mounted, low pitch stiffness and low roll stiffness are required. This can be realized by making the plate thickness of the flexure 103 thin, and by making the linking part 133a between the outrigger part 132 and the tongue part 133 narrow.
[Patent Document 1] JP2002-74870A
However, if the pitch stiffness and roll stiffness of the tongue part 133 are lowered by forming the plate thickness of the flexure 103 to be thin, in turn, a problem that the stiffness in a longitudinal direction (see arrow 100 in FIG. 23) of the flexure 103 (hereinafter referred to as “inline stiffness”) is lowered is caused. In such a case, if using a CSS drive of the type which causes the magnetic head slider placed on a magnetic disk to fly along with the rotation of the magnetic disk, the magnetic head slider mounted on the tongue part is drawn along with the rotation of the magnetic disk to thereby be stuck to the magnetic disk, causing a problem that prompt and appropriate flying cannot be realized.
If such a problem is caused, a disk drive may not be activated promptly, and further, accurate reading/writing may not be performed to the magnetic disk. Thereby, reliability of the disk drive may be lowered.